With Ultimate Nullifyer (full-fed)

As DBZ_universe above me said, Kami Tecnhi, who is omnipotent and on par with The One Above All and The Presence. I hear Kami Tenchi is even also a refelction of the author like TOAA is. Many other Tenchi Muyo! characters could also easily defeat Galactus, such as the Chousin, The Counter-Actor and possibly normal Tenchi.

Several characters from Slayers too like Ruby Eye, though mainly the Lord of Nightmares, who is also omnipotent.

Many of the Eldergods and mechs from Demonbane would be able to grab as many Galacti as they can from the omniverse, put them in a colossal bowl, fill it with milk and eat them for breakfast.

Umineko I hear has characters who can rewrite existance to their will and are on a multiversal level. The main I've heard of is Featherine.

Noein is a multiversial reality warper who is capable of absorbing an infinite multiverse until on his own dimension, Shangru-La, remains. He almost suceeded with his plans. Haruka Kaminogi is even stronger, she can she fit if any one deserves to exist or not and return the multiverse to order even after Noein screwed it over so bad.

What's that you say, Galactus eats planets? Well Getter Emperor eats galaxies and universes at its strongest. It's considered a multiversial threat, and if no one stops it than it's power keeps on growing until it obtains omnipotence and devours the Getter multiverse.

Though originally a video game, Digimon has some animes and manga based off it, and some ridiculously overpowered characters to boot. Neo, Imperialdramon and others are considered to be at least universal not only in destruction, but creative capasities too. The strongest of all though is Zeedmilleniumon, who is not only multiversial, but a paradox too as it's both dead and alive at the same time and apparently took a plot device to subdue him. Several arguments here on Anime Vice and on Comic Vine also said it could beat the Anti-Monitor (and lets face it, full-power Anti-Monitor exceeds full-power Galactus).

Deus Ex Machina is the God of time and space from Future Diary, though I don't know if he's universal or multiversal.

Berserk also has an obsure omnipotent hidden away in the background somewhere.

No doubt several characters from Saint Seiya, including Hades and Athena at their strongest.

The Dragon God from Project A-ko! is a multiversal threat.

Oh so Galactus rocks up in the Heroman universe thinking how easy this will be and how there's no one here over planetary or solar level? Well I have big news for you, Big G, you'll meet a familiar face here who decided to take a break from your existance and create his own anime universe...

Without Ultimate Nullifyer (full-fed)

Tengen Toppa Gurren Lagann could take a full-fed Galactus after a fair fight (though if he was full-fed with the Ultimate Nullifier it may be a different story). Tengen Toppa Gurren Lagann took a Big Bang attack, much like Galactus managed to survive the Big Bang. Tengen Toppa Gurren Lagann is always increasing in power, and they could always alter the probability of their victory. Super Tengen Toppa Gurren Lagann wins easily. The Anti-Spiral may also take him as they took over the Gurren Lagann universe and live in a dimension bent entirely to their will and have the Multiversal Labyrinth, from which no living sentinal lifeform can escape.

Satan from Bastard!!! is a universe destroyer and can create small universes in his hand and has countless, powerful shields. Dark Schneider and other Bastard!!! characters could possibly also take him (though once again if he had the Ultimate Nullifyer whilst fully fed that would probably be a different story. Probably, I should really read more Bastard!!! sometime). I also hear Bastard!!! has an omnipotent God lurking somewhere in the background, so he could easily take Galactus.

The cast of Jojo's Bizzare Adventure have universal time/space manipulation skills. Giorno Giovanna, for instance, can nullify any attack on him to moot on a universal level. Enrico Pucci has some time powers or something (not too sure).

Lain is a controller of time and space (according to OutskirtsBattleDome, on a universal level). She can erase those who get in her way and replace them with time clones (I need more information on this one).

Haruhi Suzumiya is a universal reality warper, but she has absolutely no control over her powers. Most likely Galactus will beat her, unless she gets lucky and turns him into a bowling pin.

Possibly defeat him in some form.

Though mainly street, city and mountain-level characters (as well as one planetary and possibly stellar character), Fullmetal Alchemist has one omnipresent and possibly omnipotent character called The Truth. Truth may be on a multiversal-level, if you include the original manga, the entrance to the gateway & beyond the gate, Gluttonys stomach, the 2003 series, the real world (featured in the 2003 series) and possibly Brotherhood, as it varies slightly from the original manga. However, Truth is non-interveining for the most part.

With the Great Spirit Hao might be able to beat him, as he's omnipotent and capable of creating supernovas and black holes.

Not 100% sure about this, but Sailor Moon characters might beat him. Might. I know nothing of them, other than they're at solar system or galaxy destroying level and at some ridiculously high point in the manga.

Xmen has an anime, and Phoneix is in it. Wasn't the Phoenix force the one who originally destroyed the old universe and caused Galan to become Galactus?

Nono from Diebuster! might defeat a hungry Galactus.

Goku could beat Galactus. The version from Rise of the Silver Surfer that is.

Kil La Kill, an upcoming anime from the creators of Gurren Lagann, has been stated by the creators to have "a higher amount of heat that Gurren Lagann." This could mean they are stronger, though we'll have to wait untill October to find out.

Any protagonist from a supernatural anime can defeat galactus, the guys basically a device used by marvel to give a chosen character a reputation boost, even though he is super powered he still gets his ass kicked every three seconds even though any one who actually faces the guy at his full power would be obliterated by the power cosmic but that never happens for a very convenient reason for the narrative.